The present disclosure relates generally to medical devices and, more particularly, to methods of analyzing physiological parameters using signal processing warping techniques.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient is commonly referred to as pulse oximetry, and the devices built based upon pulse oximetry techniques are commonly referred to as pulse oximeters. Pulse oximetry may be used to measure various blood flow characteristics, such as the blood-oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. In fact, the “pulse” in pulse oximetry refers to the time varying amount of arterial blood in the tissue during each cardiac cycle.
Pulse oximeters typically utilize a non-invasive sensor that transmits light through a patient's tissue and that photoelectrically detects the absorption of the transmitted light in such tissue. A typical pulse oximeter may use light emitting diodes (LEDs) to measure light absorption by the blood. The absorbed and/or scattered light may be detected by the pulse oximeter, and may result in a signal that is proportional to the intensity of the detected light. The received signal may be further processed, and various physiological parameters may be determined based on signal features.
The accuracy of physiological parameters determined based on the received signal may depend on a number of factors. For example, light absorption characteristics may vary depending on factors such as the location of the sensor and/or the physiology of the patient being monitored. Additionally, various types of noise and interference that can also affect accuracy may include electrical noise, physiological noise, patient motion, or other interferences. Some sources of noise are consistent, predictable, and/or minimal, while other sources of noise may be erratic, and may cause major interruptions in measuring blood flow characteristics. For example, motion of the patient may be unpredictable, and may cause interruptions that do not correspond to changes in the physiological parameters being measured. Methods of signal processing and/or signal analysis which enables the identification of non-physiological signal characteristics, such as motion, may improve the accuracy of pulse oximetry analyses.